Pump and diaphragm plunger sub-assembly



Feb. 2l, 1967 J, GoLD ETAL.

PUMP AND DIAPHRAGM PLUNGER SUB-ASSEMBLY Filed Nov. 6, 1964 2M m Y da m /0 www @y .f l w United States Patent O Filed Nov. 6, 1964, Ser. No. 409,380 2 Claims. (Cl. 103150) This invention relates to pumps and sub-assemblies therefor and more particularly to diaphragm pumps and sub-assemblies suitable for use in the fuel systems of internal combustion engines.

A problem presenting several aspects has oftenappeared with regard to fuel pumps of the type commonly used in the automotive field. A plunger is customarily employed to act with the assistance of two clamping plates to activate or reciprocate a pumping diaphragm in creating a liquid fuel pressure within a pumping chamber partially defined by the diaphragm. A pump representative of the general field of pumps to which the present invention applies is disclosed in the United States Patent No. 3,135,218 granted .lune 2, 1964, in the name of Dimitar Toschkoff. The problem referred to above pertains to the joinder of the pump plunger, on one hand, in leakproof relation to the diaphragm retaining or clamping plates and the diaphragm, on the other. The diaphragm is of flexible and yielding as well as impermeable material and is necessarily inert to the fluid being handled. Because of its nature it has the tendency to creep between clamping elements and it is difficult permanently to clamp the material to form a stable and reliable sub-assembly. It is important also to so form the sub-assembly that it be as compact as possible and also be capable to provide maximum pumping displacement by or volumetric efliciency of the complete pump.

An object of the present invention is to provide an improved pump in which a pumping diaphragm is firmly clamped and attached to an actuator plunger to prevent creeping of the diaphragm material and to minimize leakage and also to maximize the useful life of the diaphragm. Another object is to provide an improved diaphragm sub-assembly including a diaphragm and plunger which sub-assembly is a stable unit capable of maximizing the useful life and operating efficiency of a pump in which the sub-assembly is to be incorporated.

A feature of the present invention is a pump having a pumping diaphragm with spaced and concentric portions thereof firmly clamped between rigid retainer plates. Another feature is a pump sub-assembly comprising a flexible diaphragm with concentric and spaced portions of the latter firmly clamped between retainer plates with an annular bead on the diaphragm tightly engaging a plunger extending through the plates and diaphragm.

These and other important features of the invention will now be described in detail in the specification and then pointed out more particularly in the appended claims.

In the drawing:

FIGURE 1 is a sectional View of an automotive fuel pump in which one embodiment of the present invention is utilized;

FIGURE 2 is a sectional view of elements comprising a diaphragm sub-assembly used in the complete pump of FIGURE 1 and drawn to a larger scale;

FIGURE 3 is an exploded sectional view of the elements shown in FIGURE 2 and which is drawn to the same scale as FIGURE 1;

FIGURE 4 is a view similar to that of FIGURE 2 but showing another embodiment of the invention; and

FIGURE 5 is a view also similar to that of FIGURE 2 but showing a third embodiment of the invention.

FIGURE 1 shows a fuel pump having a housing 10 which is adapted by means of a flange 12 to be fixed to the side of an automotive engine and this housing defines an L-shaped chamber 14 adapted to communicate with the engine crankcase through an opening 16 as is conventional. An intermediate portion of the housing 10 is enlarged as at 18 to define a pumping spring chamber and to this enlarged portion is attached, by crimping, a pumping assembly indicated at 20. The pumping assembly 20, insofar as the present invention is concerned, may be considered to be a part of the housing 10. The peripheral margin of the flexible diaphragm 22 is clamped as at 24 between the casting portion or main body of the housing 10 and the pumping assembly 20 so that the latter and the diaphragm define a pumping chamber 26 between them. A conventional one-way inlet valve 28 is arranged in the assembly 20 to receive fuel from an inlet 30 and a similarly constructed outlet valve 32 is arranged to permit the discharge of fluid from the pump by way of an outlet 34. A plunger 36 is arranged within the housing 10 to be activated by an oscillating arm 38 and a pumping spring 42 located within the chamber 18.

The plunger 36 has a head 44 by means of which it may be activated or vertically oscillated. The lower part of theplunger 36 bears an annular shoulder 46 adjacent to the end and the extreme end 48 of the plunger is adapted to pass through openings 50, 52, 54, and 56 (FIGURE 3) of elements 58, 22, 60, and 62 respectively. Element 58 is a stiff retainer plate with an upturned peripheral flange 64 and what is termed herein as a small annular ridge 66 which faces'upwardly. Between the ridge 66 and the opening 50 is a more diminutive and upwardly directed ridge 68 which is adapted to abut the shoulder 46. The flange 64 is substantially frusto-conical and the general -contour of the plate results in a rigid disc which is not easily deformed.

The element 22 is the pumping diaphragm and is of molded rubberized fabric of a special composition to withstand the fluid to be handled by the pump and the flexing obviously necessary. Also molded into or integral with the diaphragm 22 is an annular bead 70 immediately surrounding the opening 52. The bead is small but adequate to form a sealing function as will be clear as the description proceeds. An annular bight 72 is preferably molded into the diaphragm 22 somewhat to conform with the contour of the upper retainer plate 58 as best seen in FIGURE 2.

The element 60 constitutes the lower diaphragm re tainer plate and it has an upstanding small ridge 74 Closely surrounding the opening 54. The plate 60also has' an annular depending ridge 76 which is large when considered in relation to the ridge 66 of the upper retainer plate 58. The outer periphery or margin of the plate 60 is substantially frusto-conical and extends in a direction opposite to that of the flange 64 of the upper plate.

The element 62 is a spring washer. When the plungers lower end 48 is inserted through the openings 50, 52, 54, and 56 provided therefor and the end of the plunger is upset as at (FIGURE 2), the sub-assembly of the present invention is a complete unit and, if not used in a new pump, could be placed in a used pump as a repair item. The shoulder 46, the washer 62 and the upset portion of the plunger at 80 serve as means for clamping spaced annular portions of the diaphragm 22 between the two retainer plates 58 and 60 and the lbead 70 on the diaphragm is forced by the clamping pressure into close engagement with the plunger and in so doing a tight seal is also formed with each of the plates 58 and 60 and the plunger 36. The plates 58 and 60 are so made that the clamping action on the diaphragm is firm not only at the bead area but also at two annular portions of the diaphragm cross sections of which are indicated at A and B in FIGURE 2. As heretofore constructed sub-assemblies of this nature have been made by tightly joining the central portions of the retainer plates and diaphragm to form a seal between the diaphragm and the plates with the result that the plates would diverge outwardly or spread apart at their peripheries because of their inherent resiliency and the outer annular portion of the diaphragm would not be firmly clamped. In the instant development, the plates are made as stiff as possible consistent with good design and the peripheral flanges of the plates as well as the annular ridges formed therein contribute in this direction to such an extent that the plates do not spring apart near their peripheries as pressure is applied. If desired, the plates may be preliminarily dished or concaved so that subsequent joinder will effect the positive clamping of the two annular diaphragm portions. The diaphragm m-aterial, in either event, cannot creep at the zone A and a completely permeable or leakproof sub-assembly is easily made with a minimum of parts to be handled.

The bight 72 is preferably used to secure adequate diaphragm travel in a given pump but such a loop is not essential in practicing the present invention. It should also be appreciated that the diaphragm 22 need not be molded but could be made from at sheet material and constrained by the plates and the pump housing to its desired configuration. The large annular plateau defined by the large ridge 76 which extends into the pumping chamber 26 contributes to volumetric eiciency as well understood in the fuel pump field. The small annular ridge 66 lend-s compactness to the arrangement and it is not only of value in lending stiffness to the plate 58 but it also serves as a centering means for the pumping spring 42.

In FIGURE 4, the elements utilized are the same as used in FIGURES 2 and 3 except that an upper retainer plate 90 is substituted for the retainer plate 5S. This plate 90 is not provided with a ridge to contact the shoulder 46 of the plunger. It is merely left at and the sealing effect is had by the squeezing of the diaphragm material into the slight space 92 provided between the plunger -portion 48 and the plate 90.

A bead on the diaphragm to form a seal at the plunger need not be molded as such but it should be integral with the diaphragm material. The embodiment of FIGURE 5 illustrates what is meant for, in this instance the elements utilized are the same as those in the previous iigures except that an upper plate 90 as shown in FIGURE 4 is utilized with a lower plate 94 also made flat at its inner periphery and a flexible pumping diaphragm 96 is utilized in place of the diaphragm 22. The diaphragm 96 is made flat at its inner periphery and is pierced for the reception of the plunger portion 48 with a hole slightly less in diameter than the diameter of the plunger so that when the plunger is inserted through the diaphragm material the flat material of the diaphragm is distorted by the plunger to form a bead and this bead is subsequently tightly forced into sealing engagement with the plunger when the spring washer 62 is firmly attached in the plunger upsetting operation.

It has been noted in extensive experimental work that a bead on either plate and not on the diaphragm material is inadequate to form the required seal. The bead must be on the diaphragm whether or not the material of the latter is flat prior to the forming of the sub-assembly.

We claim:

1. A fuel pump including a housing, a diaphragm of yielding flexible material cooperating with said housing in defining a pumping chamber, two stiff retainer plates, one of s-aid plates having a large annular ridge extending into said pumping chamber, a small annular ridge on the other of said plates, a coiled spring in said housing having one end centered by said small annular ridge, a plunger extending through said coiled spring, plates and diaphragm, an annular bead on said diaphragm closely surrounding said plunger and contributing to the immediate thickness of said diaphragm, and means on s-aid plunger urging said plates into clamping relation with said bead and said diaphragm so that creeping of said diaphragm material between said plates is minimized.

2. A pump sub-assembly comprising a plunger, a flexible diaphragm of one diameter and two rigid sheet metal retainer plates of smaller diameters, a central opening in said diaphragm, said plunger extending through said central opening and said plates, an annular groove of small width in one of said plates, an annular groove of larger width in the other of said plates, said grooves being open to opposite sides of said diaphragm, an annular bead integral with said diaphragm and contributing to the thickness of the latter and encompassing said plunger, means on said plunger radially and inwardly of said annular grooves clamping said plates and diaphragm together and also clamping said bead as a seal between said plunger and at least one of said plates, said grooves being radially spaced so -as to separate the clamping contact of the retainer plates on the diaphragm into two distinct annular tareas, one radially inwardly of the grooves and one radially outwardly of the grooves whereby creeping of said diaphragm near the peripheries of said plates is prevented.

References Cited by the Examiner UNITED STATES PATENTS 2,464,196 3/1949 Van Ranst 103-150 2,634,687 4/1953 Smith 103-150 2,801,594 8/1957 Lewis 103-150 2,826,153 3/1958 Johnson 103--150 3,135,218 6/1964 Toschkof 103--150 3,173,342 3/1965 Wilson 92-100 3,186,351 6/1965 Bradley 103-150 3,200,758 8/1965 Grabiel 103-150 FOREIGN PATENTS 583,530 5/1944 Great Britain.

DoNLEY J. sToCKING, Primary Examiner. MARK NEWMAN, Examiner.

Assistant Examiner.' 

1. A FUEL PUMP INCLUDING A HOUSING, A DIAPHRAGM OF YEILDING FLEXIBLE MATERIAL COOPERATING WITH SAID HOUSING IN DEFINING A PUMPING CHAMBER, TWO STIFF RETAINER PLATES, ONE OF SAID PLATES HAVING A LARGE ANNULAR RIDGE EXTENDING INTO SAID PUMPING CHAMBER,A SMALL ANNULAR RIDGE ON THE OTHER OF SAID PLATES, A COILED SPRING IN SAID HOUSING HAVING ONE END CENTERED BY SAID SMALL ANNULAR RIDGE, A PLUNGER EXTENDING THROUGH SAID COILED SPRING, PLATES AND DIAPHRAGM, AN ANNULAR BEAD ON SAID DIAPHRAGM CLOSELY SURROUNDING SAID PLUNGER AND CONTRIBUTING TO THE IMMEDIATE THICKNESS OF SAID DIAPHGRAM, AND MEANS ON SAID PLUNGER URGING SAID PLATES INTO CLAMPING RELATION WITH SAID BEAD AND SAID DIAPHRAGM SO THAT CREEPING OF SAID DIAPHRAGM MATERIAL BETWEEN SAID PLATES IS MINIMIZED. 